preserving vintage pick guards

[Baron Collins-Hill]

I just picked up a lovely '24 Gibson A snakehead in immaculate condition, and the pick guard looks brand new along with the rest of the instrument. I don't like playing instruments with pick guards, so I have taken it off, but want to make sure it is well cared for as I know they can deteriorate over time.

How should I store it to avoid doing damage?

I am also torn between selling it to someone that would actually use it rather than putting it in a box for another 100 years vs. keeping the instrument all original, which would be nice as I am only the 3rd owner and know the lineage of the instrument.

Thoughts? Advice? All is appreciated.

Thanks very much,
Baron

[JFDilmando]

Certainly don't put it in a closed case... the gases that come off the pickguard have to vent, and in a closed case they have nowhere to go, so material begins to deteriorate. Perhaps just wrapped in loose cloth and placed on an nice safe shelf would do the trick. I am not speaking form personal experience here, just spewing what I have been fed by those that know more than I.

[sblock]

Many old types of plastic -- including some pickguards, especially those made to look like faux tortoise! -- were made from nitrocellulose (cellulose nitrate; collodion), the same ingredient used for early movie film stock. Over time, this early plastic material is chemically unstable, as it slowly decomposes. Among the gasses given off in this process are NO2 (nitrogen dioxide), NO (nitrous oxide), CO (carbon monoxide) and CO2 (carbon dioxide). In addition to outgassing, among the chemicals created (left behind) are formaldehyde, formic acid, and glyoxal. Glyoxal is an aldehyde liquid that evaporates to give a green-colored gas. Nasty.

The NO2 and NO can, and will, react with the water vapor in the air to produce both nitric and nitrous acid. Add these to the formic acid that's also formed during nitrocellulose decomposition, and you have three very corrosive compounds. These strong acids can certainly rust nearby strings and frets and other metal items. They can also permanently discolor any surface nearby.

Finally, the free aldehydes (formaldehyde and glyoxal) are highly reactive will react with, and "pickle" (cross-link) all manner of organic compounds, including reacting with the wood of the instrument. They will interact with the finish, too. Not good.

I would certainly recommend removing and replacing these old pickguards. They are bad news! Forget about preserving their "vintage value" -- they are dangerous to the remainder of your valuable old instrument. Replace them with modern plastic substitutes, or with wooden pickguards. Or live without them altogether. But get them far away from your mandolin.

I respectfully disagree with some of the advice above. No, you do not have to store these things out in the air so they can continue to outgas. In fact, that will only accelerate their decay! If you want to preserve them for some reason, store them in a tightly sealed container (like a glass jar or plastic bag) that contains a desiccant (like Drierite) to absorb and eliminate any residual water vapor (it's this vapor that reacts to produce the acids, remember). And keep the container in a refrigerator! The cold temperature will do more than anything else to slow down the inevitable decomposition. And so will the elimination of UV light.